Battery control apparatus and battery control method

Abstract

To provide a battery control apparatus and a battery control method capable of simultaneously performing impedance measurement and cell balancing.SOLUTION: A battery control apparatus 10 comprises: a load / shunt resistor 16 that is provided for each battery cell 12 of a battery 12 and is connected in parallel to the battery cell 12; a switch 18 that is provided corresponding to each battery cell 14, is connected in parallel to the battery cell 14, and is connected in series to the load / shunt resistor 16; a current measurement unit 22 that is provided corresponding to each battery cell 14, and measures a current flowing through the load / shunt resistor 16; a voltage measurement unit 24 that is provided corresponding to each battery cell 14, and measures a voltage of the battery cell 14; and a control unit 26 that controls ON / OFF of the switch 18 and performs cell balancing and impedance calculation on the basis of measurement results of the current measurement unit 22 and the voltage measurement unit 24.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery control device and a battery control method. [Background technology]

[0002] Patent Document 1 proposes a battery module that includes an assembled battery system including an assembled battery in which multiple battery cells are connected in series and a balancer that equalizes the depth of charge of the multiple battery cells, a measurement circuit for measuring the impedance characteristics of the assembled battery before and after the equalization process, and a processor that detects, using the impedance characteristics before and after the equalization process, that a first battery cell that has a greater depth of charge than other battery cells has a greater degree of deterioration than the other battery cells.

[0003] Patent Document 2 proposes a battery module that includes an assembled battery system including an assembled battery in which multiple battery cells are connected in series and a BMS that equalizes the depth of charge of the multiple battery cells; a measurement circuit for measuring a first impedance characteristic of the assembled battery before the equalization process and a second reference impedance characteristic of a reference battery cell after the equalization process; and a processor that uses the first impedance characteristic and the second reference impedance characteristic to detect that a first battery cell having a greater depth of charge than other battery cells has a greater degree of deterioration than the other battery cells.

[0004] Patent document 3 proposes a battery circuit that includes a cell group consisting of a plurality of battery cells connected in series, a resistor group consisting of a plurality of resistors connected in series, and a disconnecting unit 5 that connects the cell group and the resistor group in a manner that allows them to be disconnected, and in which the disconnecting unit is configured to be able to change the number of resistors connected in series to any one target cell among the plurality of battery cells.

[0005] Patent Document 4 proposes a method including the steps of determining an initial electrical state of a Li-ion battery, changing the electrical state of the Li-ion battery by applying or removing a direct current electrical stimulus to the Li-ion battery to induce a time-varying response, measuring the time-varying response of the Li-ion battery to the changed electrical state, extracting at least one primary response parameter associated with at least a functional form of the measured response, deriving at least one secondary response parameter from the primary response parameter, and determining the likelihood of a short-circuit precursor state according to at least one of the primary response parameter and the secondary response parameter.

[0006] Patent Document 5 proposes an energy storage module that includes a first converter that converts first analog data indicating the voltage value of each battery into first digital data, and a second converter that converts second analog data indicating the current value flowing through multiple batteries into second digital data, where the first analog data and the second analog data are data at the same time. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2022-080182 [Patent Document 2] Japanese Patent Publication No. 2022-080183 [Patent Document 3] Japanese Patent Application Publication No. 2023-141211 [Patent Document 4] Japanese Patent Application Publication No. 2018-524792 [Patent Document 5] Japanese Patent Application Laid-Open No. 2015-042983 Summary of the Invention [Problem to be solved by the invention]

[0008] Generally, conventional impedance measurements are performed using a block configuration such as that shown in FIG. 4. That is, a battery 50 has a plurality of battery cells 52 connected in series, and a voltage measurement unit 54 is connected in parallel to each of the battery cells 52. A load resistor 56, a shunt resistor 58, and a switch 60 are connected in series and in parallel to the battery 50. A current measurement unit 62 measures the current flowing through the shunt resistor 58. An impedance calculation unit 66 controls a switch on / off control unit 64 to turn the switch 60 on and off to allow a current to flow, and the internal impedance of the battery 50 is measured from the current value measured by the current measurement unit 62 when the current is flowing and the voltage value of each battery cell 52 measured by the voltage measurement unit 54.

[0009] Conventional cell balancing is performed using a block configuration as shown in Fig. 5. That is, a voltage measurement unit 74 is connected in parallel to each of the battery cells 52 of a battery 50 having a plurality of battery cells 52 connected in series. A load resistor 68 and a switch 70 are connected in series and also in parallel to each of the battery cells 52 of the battery 50. A cell balancing control unit 76 controls a switch on / off control unit 72 corresponding to a battery cell whose capacity is to be reduced based on the measurement result of the voltage measurement unit 74, thereby turning on the switch 70, thereby reducing the capacity.

[0010] In this way, the conventional impedance measurement block and cell balancing block are implemented as separate blocks and are controlled separately.

[0011] However, the above-described configuration requires two blocks, one for impedance measurement and one for cell balancing, which poses a problem of increasing the size of the circuit configuration.

[0012] In addition, because impedance measurement and cell balancing are controlled separately, there is a possibility that the battery capacity may be reduced too much.

[0013] Therefore, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a battery control device and a battery control method that are capable of simultaneously performing impedance measurement and cell balancing. [Means for solving the problem]

[0014] A battery control device according to a first aspect includes a resistor provided in each battery cell of a battery having a plurality of battery cells connected in series and connected in parallel to the battery cell; a switch provided corresponding to each of the plurality of battery cells, connected in parallel to the battery cell and connected in series to the resistor; a current measuring unit provided corresponding to each of the battery cells and measuring the current flowing through the resistor; a voltage measuring unit provided corresponding to each of the battery cells and measuring the voltage of the battery cell; and a control unit that controls the on / off of the switches and performs cell balancing and impedance calculation based on the measurement results of the current measuring unit and the voltage measuring unit.

[0015] A battery control method according to a second aspect is a battery control method for a battery control device that includes a resistor provided in each battery cell of a battery having a plurality of battery cells connected in series and connected in parallel to the battery cell, a switch provided corresponding to each of the plurality of battery cells, connected in parallel to the battery cell and connected in series to the resistor, a current measurement unit provided corresponding to each of the battery cells and measuring the current flowing through the resistor, a voltage measurement unit provided corresponding to each of the battery cells and measuring the voltage of the battery cell, and a control unit, wherein the control unit controls the on / off of the switches and performs cell balancing and impedance calculation based on the measurement results of the current measurement unit and the voltage measurement unit. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a schematic configuration of a battery control processing device according to a first embodiment. [Figure 2]5 is a flowchart showing an example of a flow of processing performed by a control unit of the battery control device according to the first embodiment. [Figure 3] 10 is a flowchart showing an example of the flow of processing performed by a control unit of a battery control device according to a second embodiment. [Figure 4] FIG. 1 is a block diagram showing an example of a conventional impedance measurement block. [Figure 5] FIG. 1 is a block diagram showing an example of a conventional cell balance block. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will now be described in detail with reference to the accompanying drawings. (First embodiment) FIG. 1 is a block diagram showing a schematic configuration of a battery control processing device according to this embodiment.

[0018] The battery control device 10 according to this embodiment includes a battery 12, a load shunt resistor 16, a switch 18, a switch on / off control unit 20, a current measuring unit 22, a voltage measuring unit 24, and a control unit .

[0019] The battery 12 includes a plurality of battery cells 14. The battery cells 14 are connected in series.

[0020] The load shunt resistors 16 are provided corresponding to the respective battery cells 14 of the battery 12 and are connected in parallel to the battery cells 14. In this embodiment, the load shunt resistors 16 serve both as load resistors for cell balancing and as shunt resistors for current detection.

[0021] The switches 18 are provided corresponding to the respective battery cells 14 of the battery 12, and are connected in parallel to the battery cells 14 and in series to the load shunt resistor 16. The switches 18 are controlled to be turned on and off by a switch on / off control unit 20.

[0022] The switch on / off control units 20 are provided corresponding to the respective switches 18 and control the on / off of the switches 18. The switch on / off control units 20 control the on / off of the switches 18 in accordance with instructions from the control unit 26. In this embodiment, the switch on / off control units 20 control the on / off of the switches 18 by a method of generating a step response waveform. Note that the switch on / off control units 20 may be omitted, and the control unit 26 may control the on / off of the switches 18.

[0023] The current measuring units 22 are provided corresponding to the respective battery cells 14, and measure the current flowing through the load / shunt resistors 16. The current measuring units 22 output the measurement results of the current flowing through the load / shunt resistors 16 to the control unit 26.

[0024] The voltage measurement units 24 are provided corresponding to the respective battery cells 14 of the battery 12, and are connected in parallel to the battery cells 14 to measure the voltages of the battery cells 14. The voltage measurement units 24 output the measurement results of the voltages of the battery cells 14 to the control unit 26.

[0025] The control unit 26 controls each switch on / off control unit 20 to control the on / off of the switch 18, and performs cell balancing of the battery cells 14 and impedance calculation based on the measurement results of the current measurement unit 22 and the voltage measurement unit 24.

[0026] In this embodiment, the control unit 26 turns off the switch 18 of each battery cell 14, measures the voltage value of each battery cell 14, and identifies one battery whose voltage value is higher than the other batteries by a predetermined threshold or more as a battery with cell imbalance.The control unit 26 then calculates the time for cell balancing from the voltage difference between the battery cells 14, turns on the switch 18 of the identified battery cell 14 for the calculated time, and performs cell balancing by discharging, while also calculating the impedance from the voltage value and current value measured by the voltage measurement unit 24 and the current measurement unit 22.

[0027] Next, a description will be given of specific processing performed by the control unit 26 of the battery control device 10 according to this embodiment configured as described above. Fig. 2 is a flowchart showing an example of the flow of processing performed by the control unit 26 of the battery control device 10 according to this embodiment.

[0028] In step 100, the control unit 26 turns off the switches for each battery cell 14, and then the process proceeds to step 102. That is, the control unit 26 controls the switch on / off control unit 20 to turn off all of the switches 18 corresponding to each battery cell 14.

[0029] In step 102, the control unit 26 acquires the measurement results of the voltage of each battery cell 14, and then the process proceeds to step 104. That is, the control unit 26 acquires the measurement results of the voltage by the voltage measurement unit 24 corresponding to each battery cell 14.

[0030] In step 104, the control unit 26 compares the voltages of the battery cells 14 and then proceeds to step .

[0031] In step 106, the control unit 26 determines whether cell balancing is necessary. This determination is made, for example, by determining whether there is a battery cell 14 whose voltage is equal to or higher than a predetermined threshold, based on the comparison results of each battery cell 14. If the determination is negative, the example process ends, and if the determination is positive, the process proceeds to step 108.

[0032] In step 108, the control unit 26 identifies one battery cell 14 whose voltage value is equal to or higher than a predetermined threshold value, and then proceeds to step 110.

[0033] In step 110, the control unit 26 calculates the time for performing cell balancing, and then the process proceeds to step 112. The time for performing cell balancing is calculated from the voltage difference between the battery cells 14.

[0034] In step 112, the control unit 26 turns on the switch 18 corresponding to the identified battery cell 14 for the calculated time, and then the process proceeds to step 114. That is, the control unit 26 controls the switch on / off control unit 20 to turn on the switch 18 corresponding to the identified battery cell 14 for the calculated time. As a result, the capacity of one battery cell 14 whose voltage value is higher than the threshold is discharged through the load / shunt resistor 16, thereby performing cell balancing and equalizing the voltage difference between each battery cell 14 to within a predetermined threshold range.

[0035] In step 114, the control unit 26 measures the voltage and current when the switch 18 is on, calculates the impedance, and then ends the series of processes. That is, the control unit 26 acquires the measurement results of the current measurement unit 22 and the voltage measurement unit 24 when the switch 18 is on, and calculates the impedance of the battery cell 14.

[0036] By performing the processing in this manner, the battery control device 10 according to this embodiment can perform cell balancing and impedance measurement simultaneously by utilizing the block that performs cell balancing, thereby reducing the circuit size and shortening the time required for cell balancing and impedance measurement.

[0037] (Second embodiment) Next, a battery control device 10 according to a second embodiment will be described. Note that the configuration of the battery control device 10 according to the second embodiment is similar to that of the first embodiment, so only the differences will be described and detailed description will be omitted.

[0038] In this embodiment, the control unit 26 turns off the switch 18 of each battery cell 14, measures the voltage value of each battery cell 14, and identifies one battery whose voltage value is higher than the other batteries by a predetermined threshold or more as a battery with cell imbalance. Then, the control unit 26 calculates the time for cell balancing from the voltage difference between the battery cells 14, turns on the switch 18 of the identified battery cell 14 for the calculated time plus the time required for impedance measurement (e.g., the minimum required time), and performs cell balancing by discharging, while also calculating impedance from the voltage and current values ​​measured by the voltage measurement unit 24 and the current measurement unit 22. At the same time, the control unit 26 also turns on the other battery cells 14 for the time for cell balancing plus the time required for impedance measurement, and also calculates impedance from the voltage and current values ​​measured by the voltage measurement unit 24 and the current measurement unit 22.

[0039] 3 is a flowchart showing an example of the flow of processing performed by the control unit 26 of the battery control device 10 according to this embodiment. Note that the same processes as those in the first embodiment will be described with the same reference numerals.

[0040] In step 100, the control unit 26 turns off the switches for each battery cell 14, and then the process proceeds to step 102. That is, the control unit 26 controls the switch on / off control unit 20 to turn off all of the switches 18 corresponding to each battery cell 14.

[0041] In step 102, the control unit 26 acquires the measurement results of the voltage of each battery cell 14, and then the process proceeds to step 104. That is, the control unit 26 acquires the measurement results of the voltage by the voltage measurement unit 24 corresponding to each battery cell 14.

[0042] In step 104, the control unit 26 compares the voltages of the battery cells 14 and then proceeds to step .

[0043] In step 106, the control unit 26 determines whether cell balancing is necessary. This determination is made, for example, by determining whether there is a battery cell 14 whose voltage is equal to or higher than a predetermined threshold, based on the comparison results of each battery cell 14. If the determination is negative, the example process ends, and if the determination is positive, the process proceeds to step 108.

[0044] In step 108, the control unit 26 identifies one battery cell 14 whose voltage value is equal to or higher than a predetermined threshold value, and then proceeds to step 110.

[0045] In step 110, the control unit 26 calculates the time for performing cell balancing, and then the process proceeds to step 111. The time for performing cell balancing is calculated from the voltage difference between the battery cells 14.

[0046] In step 111, the control unit 26 turns on the switch 18 corresponding to the identified battery cell 14 for the calculated time plus the time required for impedance measurement, and turns on the switches 18 corresponding to the other battery cells 14 for the cell balancing time plus the time required for impedance measurement, and then proceeds to step 113. That is, the control unit 26 controls the switch on / off control unit 20 to turn on the switch 18 corresponding to the identified battery cell 14 for the calculated time plus the time required for impedance measurement (for example, the minimum required time), and simultaneously controls the switch on / off control unit 20 to turn on the other battery cells 14 for the same time as the identified battery cell 14. As a result, the capacity of one battery cell 14 whose voltage value is higher than the threshold is discharged through the load / shunt resistor 16, thereby performing cell balancing and equalizing the voltage difference between the battery cells 14 to within a predetermined threshold range.

[0047] In step 113, the control unit 26 measures the voltage and current when the switch 18 is on, calculates the impedance of each battery cell 14, and then ends the series of processes. That is, the control unit 26 acquires the measurement results of the current measurement unit 22 and voltage measurement unit 24 corresponding to each battery cell 14 when the switch 18 is on, and calculates the impedance of each battery cell 14.

[0048] By performing the processing in this manner, the battery control device 10 according to this embodiment can perform cell balancing and impedance measurement of the unbalanced battery cell 14, while also measuring the impedance of all the battery cells 14. This reduces the time required for cell balancing and impedance measurement.

[0049] In the above embodiments, the on / off of the switch 18 is performed by generating a step response waveform, but the present invention is not limited to this. For example, a method of generating an impulse response waveform or a pseudo-sine wave waveform may be applied.

[0050] In the above embodiments, the cell balancing time is calculated from the voltage difference between the batteries, but this is not limiting. For example, the time required for impedance measurement may be used, and after cell balancing, the voltage of the battery cells 14 may be measured again. If the balance is not achieved, the cell balancing operation may be repeated.

[0051] Furthermore, the processing performed by the control unit 26 in each of the above embodiments may be software processing performed by executing a program, or may be hardware processing. If hardware processing is used, the processing may be performed by hardware such as a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), or an FPGA (Field-Programmable Gate Array). Alternatively, the processing may be a combination of both software and hardware. If software processing is used, the program may be stored in various storage media and distributed.

[0052] Furthermore, the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0053] The following additional notes are provided regarding the above-described embodiments.

[0054] (Appendix 1) a resistor provided in each battery cell of a battery having a plurality of battery cells connected in series and connected in parallel to the battery cell; a switch provided corresponding to each of the plurality of battery cells, connected in parallel to the battery cell, and connected in series to the resistor; a current measuring unit provided corresponding to each of the battery cells, the current measuring unit measuring a current flowing through the resistor; a voltage measurement unit provided corresponding to each of the battery cells, the voltage measurement unit measuring the voltage of the battery cell; a control unit that controls the on / off of the switch and performs cell balancing and impedance calculation based on the measurement results of the current measurement unit and the voltage measurement unit; A battery control device comprising:

[0055] (Appendix 2) 2. The battery control device according to claim 1, wherein the resistor serves as both a load resistor and a shunt resistor.

[0056] (Appendix 3) Further provided is a switch on / off control unit that turns the switch on and off, 3. The battery control device according to claim 1, wherein the control unit controls the switch on / off control unit to control the on / off of the switch.

[0057] (Appendix 4) The battery control device according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the control unit identifies one of the battery cells having a voltage value higher than a threshold value, calculates a time for cell balancing from a voltage difference between the battery cells, turns on the switch corresponding to the identified battery cell for the calculated time, performs cell balancing by discharging, and calculates an impedance of the battery cell based on the measurement results of the current measurement unit and the voltage measurement unit.

[0058] (Appendix 5) The battery control device according to any one of Supplementary Note 1 to Supplementary Note 3, wherein the control unit identifies one of the battery cells having a voltage value higher than a threshold value, calculates a time for cell balancing from a voltage difference between the battery cells, turns on the switch corresponding to the identified battery cell for the calculated time plus the time required for impedance measurement, and simultaneously turns on the switches corresponding to the other battery cells for the calculated time plus the time required for impedance measurement, thereby performing cell balancing by discharging, and calculates the impedance of each of the battery cells based on the measurement results of the current measurement unit and the voltage measurement unit.

[0059] (Appendix 6) A battery control method for a battery control device including a battery having a plurality of battery cells connected in series, the battery having a plurality of battery cells, a resistor provided in each of the battery cells and connected in parallel to the battery cell, a switch provided corresponding to each of the plurality of battery cells, connected in parallel to the battery cell and connected in series to the resistor, a current measuring unit provided corresponding to each of the battery cells and measuring a current flowing through the resistor, a voltage measuring unit provided corresponding to each of the battery cells and measuring a voltage of the battery cell, and a control unit, The control unit controls the on / off of the switch and performs cell balancing and impedance calculation based on the measurement results of the current measurement unit and the voltage measurement unit. [Explanation of symbols]

[0060] 10 Battery control device 12 Battery 14 battery cells 16 Load / shunt resistor 18 Switch 20 Switch on / off control section 22 Current measurement section 24 Voltage measurement section 26 Control Unit

Claims

1. a resistor provided in each battery cell of a battery having a plurality of battery cells connected in series and connected in parallel to the battery cell; a switch provided corresponding to each of the plurality of battery cells, connected in parallel to the battery cell, and connected in series to the resistor; a current measuring unit provided corresponding to each of the battery cells, the current measuring unit measuring a current flowing through the resistor; a voltage measurement unit provided corresponding to each of the battery cells, the voltage measurement unit measuring the voltage of the battery cell; a control unit that controls the on / off of the switch and performs cell balancing and impedance calculation based on the measurement results of the current measurement unit and the voltage measurement unit; A battery control device comprising:

2. 2. The battery control device according to claim 1, wherein the resistor serves as both a load resistor and a shunt resistor.

3. Further provided is a switch on / off control unit that turns the switch on and off, The battery control device according to claim 1 , wherein the control unit controls the switch on / off control unit to turn the switch on and off.

4. 2. The battery control device according to claim 1, wherein the control unit identifies one of the battery cells having a voltage value equal to or higher than a threshold value, calculates a time for cell balancing from a voltage difference between the battery cells, turns on the switch corresponding to the identified battery cell for the calculated time, performs cell balancing by discharging, and calculates an impedance of the battery cell based on the measurement results of the current measurement unit and the voltage measurement unit.

5. 2. The battery control device according to claim 1, wherein the control unit identifies one of the battery cells having a voltage value higher than a threshold value, calculates a time for cell balancing from the voltage difference between the battery cells, turns on the switch corresponding to the identified battery cell for the calculated time plus the time required for impedance measurement, and simultaneously turns on the switches corresponding to the other battery cells for the calculated time plus the time required for impedance measurement, thereby performing cell balancing by discharging, and calculates the impedance of each of the battery cells based on the measurement results of the current measurement unit and the voltage measurement unit.

6. A battery control method for a battery control device including a battery having a plurality of battery cells connected in series, the battery having a plurality of battery cells, a resistor provided in each of the battery cells and connected in parallel to the battery cell, a switch provided corresponding to each of the plurality of battery cells, connected in parallel to the battery cell and connected in series to the resistor, a current measuring unit provided corresponding to each of the battery cells and measuring a current flowing through the resistor, a voltage measuring unit provided corresponding to each of the battery cells and measuring a voltage of the battery cell, and a control unit, The control unit controls the on / off of the switch and performs cell balancing and impedance calculation based on the measurement results of the current measurement unit and the voltage measurement unit.

Images